From: Masami Hiramatsu <mhiramat@kernel.org>
To: Marcin Nowakowski <marcin.nowakowski@imgtec.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
"Peter Zijlstra (Intel)" <peterz@infradead.org>,
Thomas Meyer <thomas@m3y3r.de>, Ingo Molnar <mingo@kernel.org>,
"Steven Rostedt (VMware)" <rostedt@goodmis.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Paul Gortmaker <paul.gortmaker@windriver.com>,
Thomas Gleixner <tglx@linutronix.de>,
<linux-kernel@vger.kernel.org>, <linux-mips@linux-mips.org>
Subject: Re: [PATCH] kernel/extable.c: mark core_kernel_text notrace
Date: Thu, 22 Jun 2017 19:24:45 +0900 [thread overview]
Message-ID: <20170622192445.c53a738717cb031c55680ce9@kernel.org> (raw)
In-Reply-To: <1498028607-6765-1-git-send-email-marcin.nowakowski@imgtec.com>
On Wed, 21 Jun 2017 09:03:26 +0200
Marcin Nowakowski <marcin.nowakowski@imgtec.com> wrote:
> core_kernel_text is used by MIPS in its function graph trace processing,
> so having this method traced leads to an infinite set of recursive calls
> such as:
>
> [ 2.972075] Call Trace:
> [ 2.972111]
> [ 2.976731] [<80506584>] ftrace_return_to_handler+0x50/0x128
> [ 2.983379] [<8045478c>] core_kernel_text+0x10/0x1b8
> [ 2.989146] [<804119b8>] prepare_ftrace_return+0x6c/0x114
> [ 2.995402] [<80411b2c>] ftrace_graph_caller+0x20/0x44
> [ 3.001362] [<80411b60>] return_to_handler+0x10/0x30
> [ 3.007159] [<80411b50>] return_to_handler+0x0/0x30
> [ 3.012827] [<80411b50>] return_to_handler+0x0/0x30
> [ 3.018621] [<804e589c>] ftrace_ops_no_ops+0x114/0x1bc
> [ 3.024602] [<8045478c>] core_kernel_text+0x10/0x1b8
> [ 3.030377] [<8045478c>] core_kernel_text+0x10/0x1b8
> [ 3.036140] [<8045478c>] core_kernel_text+0x10/0x1b8
> [ 3.041915] [<804e589c>] ftrace_ops_no_ops+0x114/0x1bc
> [ 3.047923] [<8045478c>] core_kernel_text+0x10/0x1b8
> [ 3.053682] [<804119b8>] prepare_ftrace_return+0x6c/0x114
> [ 3.059938] [<80411b2c>] ftrace_graph_caller+0x20/0x44
> (...)
>
> Mark the function notrace to avoid it being traced.
>
> Signed-off-by: Marcin Nowakowski <marcin.nowakowski@imgtec.com>
Looks correct to me.
Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Thanks,
> ---
> kernel/extable.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/kernel/extable.c b/kernel/extable.c
> index 2676d7f..4efaf26 100644
> --- a/kernel/extable.c
> +++ b/kernel/extable.c
> @@ -70,7 +70,7 @@ static inline int init_kernel_text(unsigned long addr)
> return 0;
> }
>
> -int core_kernel_text(unsigned long addr)
> +int notrace core_kernel_text(unsigned long addr)
> {
> if (addr >= (unsigned long)_stext &&
> addr < (unsigned long)_etext)
> --
> 2.7.4
>
--
Masami Hiramatsu <mhiramat@kernel.org>
next prev parent reply other threads:[~2017-06-22 10:24 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-06-21 7:03 Marcin Nowakowski
2017-06-22 10:24 ` Masami Hiramatsu [this message]
2017-06-22 22:10 ` Steven Rostedt
2017-06-22 22:16 ` Thomas Gleixner
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